RAW devices and Xenserver 5.6 fp1

eaperezh · Wed Feb 09, 2011 6:21 pm

Hi there,
I have a win2003 64 bit target exporting 8TB in iscsi targets.
We are going to perform some changes and wanted to ask here if is there any benefit in terms of performance to export the iscsi targets to my two xenservers as RAW devices instead of formatting them in the target as ntfs, creating a .img file and then exporting the img.
my first answer will be that since xenserver will use lvm over iscsi, then exporting as raw devices from the starwind server will yield better performance as the disks are being accessed directly.

comments?

Thu Feb 10, 2011 7:20 am

Does not matter with the most recent versions of StarWind. Really... Image files give you a little bit more of flexibility. Performance is plain identical.

eaperezh · Thu Feb 10, 2011 12:37 pm

Hi anton, since we are installing all the stuff i will measure performance from the xenserver to the iscsi target with something like dd. I will then reply to this post with full hardware/network specs.
I will perform tests with raw exported and with the .img exported as well as with normal jumbo frames and 9k jumbo frames since we are using xenserver 5.6 fp1. Also, some load balancing methods will be used among the network cards. in another post i will ask some guidance for the bonded interfaces.
Please allow me at least one day to prepare de document and answer to this thread.

Thanks,

Thu Feb 10, 2011 4:04 pm

It's not going to measure anything as dd fires I/O requests sequentially. Something you'll hardly ever see in a real life.

No problem! Take your time

eaperezh wrote:Hi anton, since we are installing all the stuff i will measure performance from the xenserver to the iscsi target with something like dd. I will then reply to this post with full hardware/network specs.
I will perform tests with raw exported and with the .img exported as well as with normal jumbo frames and 9k jumbo frames since we are using xenserver 5.6 fp1. Also, some load balancing methods will be used among the network cards. in another post i will ask some guidance for the bonded interfaces.
Please allow me at least one day to prepare de document and answer to this thread.

Thanks,

eaperezh · Thu Feb 10, 2011 4:59 pm

What do you recommend to perform real random tests?

Thu Feb 10, 2011 6:24 pm

Some database with tiny records. Say spam e-mail collection with 1M+ entries.

P.S. No we don't have one for free. And we don't sell it either.

eaperezh wrote:What do you recommend to perform real random tests?